Extreme weather resulting in flash flooding is posing a serious risk for several parts of NSW on Saturday.
For the next six to 12 hours, heavy rain can be expected in the eastern Hunter, Sydney Metropolitan, eastern Central Tablelands and Illawarra districts, the Bureau of Meteorology (BoM) said.
Later on Saturday night, parts of the Mid North Coast of the state may see rain increase.
"In these areas, there may be periods of INTENSE RAINFALL, potentially leading to LIFE THREATENING flash flooding," BoM said.
"Roads are likely to be cut off by water, and there will be an increased risk of landslips during this period."
It is expected Sydney will receive between 90 to 150mm of rain on Saturday, with a further 45 to 60mm forecast for Sunday.
The Golden Slipper has been postponed for the first time in 58 years, due to the wet weather resulting in "unsafe" conditions.
It is likely along the coastal fringe of the Hunter district may experience damaging winds exceeding 90km/h Saturday afternoon and evening.
The strong winds in the area may result in damaging surf, with waves reaching heights of five metres and a chance of coastal erosion.
State Emergency Services officials have urged people to stay at home.
"First and foremost, we are asking people to limit unnecessary travel," NSW SES Deputy Commissioner Daniel Austin told ABC News.
"So if you don't need to be out in it, please don't. We recognise some people do need to travel, and there are absolutely legitimate reasons for doing so, but we are asking those who don't need to, not to."
Thousands of calls for help
The State Emergency Service has responded to more than 3200 calls for help since the wet weather began, including 335 flood rescues overnight.
That is a "huge number", NSW SES spokesman Andrew McCullough told AAP.
"A lot of those jobs are for people who are stuck in their houses, caravans, animals isolated by floodwater, people stuck in cars - it's really for a wide mix of things," he said.
Most of the calls are coming in from Taree, Wingham, Port Macquarie, Macksville, Settlement Point, Wauchope, Laurieton and North Haven.
"Every minute we get two or three more rescues coming through at the moment," Mr McCullough said.
"This is not a typical sort of flood, these are life-threatening floodwaters and (it's) a very serious situation."
Calls for help from the Hunter and Sydney regions are starting to roll in too, as the system moves south, Mr McCullough said.
Major flooding has hit several towns along the NSW mid-north coast, with the Hastings and Camden Haven rivers reaching record levels.
Those in low-lying properties around Taree, Dumaresq Island, Cundletown, Central Wingham and Wingham Peninsular were ordered to evacuate on Saturday morning.
Evacuation orders were also issued in Kempsey, Port Macquarie, North Haven, Dunbogan, Camden Head and Laurieton on Friday.
The Hastings River peaked at 12.1m near Port Macquarie breaking an eight-year-old record, and major flooding at Laurieton exceeded a record set in 1978.
Major flooding also hit Macksville and Bowraville overnight.
It is expected river levels at Dungog, Mill Dam Falls and Gostwyck Bridge will exceed the major flood levels on Saturday morning.
The BoM advises you follow flood safety advice:
Avoid drowning. Stay out of rising water, seek refuge in the highest available place.
Prevent damage to your vehicle. Move it under cover, away from areas likely to flood.
Avoid being swept away. Stay out of fast-flowing creeks and storm drains.
Never drive, ride or walk through flood water. Flood water can be deceptive and dangerous.
NSW SES Wingham Unit said the Wingham township was "totally isolated" early Saturday morning, with flood water continuing to rise.
An evacuation centre has been established at Wingham Golf Club.
Rain to continue into next week
It is expected the deluge will continue well into next week and there is a chance it could deliver the heaviest rainfall since February 2020, when Greater Sydney was hit.
While the worst of the system has passed, emergency services have warned road and surf conditions will remain dangerous and are telling motorists and boaties to stay home.
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